How to care for sweet peas during chrysanthemums? - Plant Care Guide

Caring for sweet peas during chrysanthemums season essentially means providing late-season care for sweet peas. As chrysanthemums typically bloom in fall, this period often coincides with the natural decline of sweet peas due to heat stress or the end of their annual life cycle. Therefore, care involves extending the sweet pea season as long as possible with consistent watering and deadheading, or transitioning to enjoying chrysanthemums as the sweet peas naturally fade.

What Are Sweet Peas and Chrysanthemums?

Understanding what sweet peas and chrysanthemums are, particularly their differing growing seasons and climate preferences, is key to comprehending how their care overlaps or diverges in a garden. While both are beloved for their beautiful flowers, they are distinct plants with different needs.

Here's a closer look at what sweet peas and chrysanthemums are:

What Are Sweet Peas (Lathyrus odoratus)?

• Plant Type: A beloved annual climbing plant. It completes its entire life cycle (germinate, grow, flower, set seed, die) within a single growing season.
• Flowers: Known for their incredibly fragrant, delicate, and often ruffled, pea-like flowers. Available in a wide spectrum of colors.
• Fragrance: Their exquisite, sweet fragrance is their most prized attribute.
• Growth Habit: Vining plants that climb using small, wiry tendrils, typically growing 3 to 10 feet tall depending on the variety.
• Season Preference: Cool-season annuals. They thrive in cool to moderate temperatures (ideally 55-65°F / 13-18°C) and are highly sensitive to heat.
  • Heat Sensitivity: When temperatures consistently rise above 75-80°F (24-27°C), sweet peas tend to stop blooming, rapidly decline, yellow, and die back. This often marks the end of their season.
  • Bloom Time: Primarily bloom from late spring through early summer. In some cooler climates, they may persist into mid-summer.
• Seeds: Produce pods containing seeds, which are mildly toxic if ingested.
• Care Focus: Requires rich, well-draining soil, consistent moisture, full sun (afternoon shade in hot climates), and support for climbing.

What Are Chrysanthemums (Chrysanthemum spp. - often called "Mums")?

• Plant Type: Mostly herbaceous perennials (their top growth dies back in winter, but roots survive), though some are grown as annuals.
• Flowers: Produce a vast array of flower forms (daisy-like, pompon, quill, spider, anemone, etc.) in almost every color imaginable except blue. They have a characteristic earthy, often spicy, scent.
• Fragrance: Often more herbaceous or spicy than sweet.
• Growth Habit: Typically grow as bushy, mounding plants, ranging from compact (1 foot tall) to larger (3+ feet tall).
• Season Preference: Cool-season bloomers. Unlike sweet peas, chrysanthemums are specifically known for their late-season blooming.
  • Temperature Preference: Thrive in cooler temperatures of late summer and fall.
  • Photoperiodism: Most garden mums are short-day plants, meaning they initiate flower buds in response to shortening daylight hours and cooler night temperatures of late summer and fall.
  • Bloom Time: Primarily bloom from late summer through fall, providing vibrant color until the first hard frost.
• Care Focus: Needs full sun, well-draining soil, consistent moisture, and often pinching in spring/early summer to promote bushiness and abundant fall flowers.

Overlapping Seasons:

The concept of caring for "sweet peas during chrysanthemums" means managing sweet peas during the time of year when chrysanthemums are coming into their peak bloom, which is typically late summer and fall. For many sweet pea varieties, this coincides with their natural decline or end of life due to summer heat.

Table: Sweet Pea vs. Chrysanthemum (Seasonality)

Therefore, caring for sweet peas during chrysanthemums primarily involves efforts to extend the sweet pea season as long as possible, or understanding that their natural end is approaching as the garden shifts to fall bloomers.

What Causes Sweet Peas to Decline as Chrysanthemums Begin to Bloom?

As chrysanthemums begin to bloom in late summer and fall, it typically coincides with the natural decline of sweet peas. This is not due to any direct negative interaction between the two plants but rather reflects the sweet pea's inherent intolerance for the increasing heat of summer and the natural completion of its annual life cycle.

Here are the primary causes for sweet peas to decline as chrysanthemums begin to bloom:

1. Heat Stress (The Primary Reason):
   • Sweet Pea Preference: Sweet peas are cool-season annuals that thrive in temperatures between 55-65°F (13-18°C).
   • Summer Reality: In most regions where chrysanthemums bloom (late summer/fall), the preceding months of July and August bring prolonged periods of high heat, often with temperatures consistently above 75-80°F (24-27°C).
   • Impact: Sweet peas are highly sensitive to this heat. High temperatures cause them to:
     • Stop Blooming: The plant will cease producing new flowers.
     • Rapid Decline: Leaves yellow, dry up, turn brown, and drop prematurely. The plant looks stressed and sickly.
     • "Melting Out": Often, the entire vine will rapidly "melt down" or collapse, even if watered.
   • Why Chrysanthemums Thrive: Chrysanthemums, conversely, are short-day plants that prefer the cooling temperatures and shortening days of late summer/fall for bloom initiation. They are just starting their show when sweet peas are ending theirs.
2. Completion of Annual Life Cycle:
   • Natural Decline: Sweet peas are annuals. Their biological purpose is to grow, flower, and set seed within one season. Once they have completed a significant amount of flowering and especially once they start forming abundant seed pods, their energy is diverted away from vegetative growth and bloom production.
   • Energy Depletion: After putting on a spectacular spring/early summer display and then focusing on seed production, the plant's energy reserves become depleted, leading to its natural decline and death, often coinciding with the onset of summer heat.
3. Increased Pest and Disease Pressure (Exacerbated by Heat/Stress):
   • Vulnerability: Sweet peas that are already stressed by heat are more susceptible to pests and diseases.
   • Common Late-Season Issues:
     • Spider Mites: Thrive in hot, dry conditions and can rapidly decimate sweet pea foliage.
     • Powdery Mildew: Common in late season when days are hot and nights are cool/humid, causing white powdery spots, yellowing, and leaf drop.
     • Aphids: Can build up populations and weaken plants.
   • Impact: These infestations accelerate the decline of the sweet pea plant.
4. Inconsistent Watering During Heat:
   • Problem: Even if trying to push sweet peas into summer, inadequate or inconsistent watering during high heat can cause rapid wilting, leaf drop, and overall decline.
   • Solution: Sweet peas need consistent moisture but not soggy soil.

The natural decline of sweet peas as chrysanthemums begin to bloom is largely a function of their biological programming as cool-season annuals that cannot tolerate sustained summer heat, compounded by the completion of their life cycle.

How Can I Extend the Sweet Pea Season?

Extending the sweet pea season beyond their typical late spring/early summer bloom requires strategic planning and diligent care, especially when trying to push them into the warmer months when chrysanthemums begin to bloom. The goal is to mitigate heat stress and prevent premature decline.

Here’s how you can extend the sweet pea season:

1. Choose Heat-Tolerant Varieties:
   • Why: Modern breeding has developed sweet pea cultivars that are more tolerant of warmer temperatures and can continue blooming longer into summer.
   • Examples: Look for series like 'Spencer', 'Old Spice', 'Bijou', or those specifically labeled as "heat-tolerant."
2. Optimal Planting Time (Crucial):
   • Early Planting: Plant sweet peas as early as possible in spring, as soon as the soil is workable. In mild-winter climates (USDA Zone 7 and warmer), plant seeds in fall for very early spring blooms. This gives them a long, cool growing period before summer heat sets in.
3. Provide Afternoon Shade:
   • Why: Protecting sweet peas from the intense, scorching afternoon sun is critical for extending their bloom season into summer.
   • Method: Plant sweet peas in a location that receives morning sun only (east-facing) or dappled shade during the hottest part of the afternoon (12 PM to 4 PM). You can also use a temporary shade cloth for vegetables during heat waves.
4. Consistent and Adequate Watering:
   • Why: Sweet peas are not drought-tolerant and need consistent moisture. Drought stress will cause rapid decline.
   • Method: Water deeply and regularly, especially during dry spells and periods of warmer weather. Ensure the soil remains consistently moist but never soggy. Use a soil moisture meter to avoid guesswork.
   • Watering Technique: Use a soaker hose or drip irrigation at the base of the plant to avoid wetting foliage, which can encourage fungal diseases in humid conditions.
5. Mulch Heavily:
   • Why: A 2-3 inch layer of organic mulch (e.g., straw, shredded leaves) helps keep the soil cooler and conserves soil moisture, both of which are crucial for fighting heat stress.
   • Consider: Clean straw for gardening.
6. Deadhead Religiously (Cut for Bouquets):
   • Why: The fastest way to end a sweet pea season is to let it go to seed. Deadheading (removing spent flowers) prevents the plant from putting energy into seed production and encourages it to produce more blooms.
   • Method: Snip off faded flowers every day or two. Even better, cut sweet pea flowers regularly for bouquets. The more you cut, the more they will produce.
7. Provide Good Air Circulation:
   • Why: Sweet peas are susceptible to powdery and downy mildew in hot, humid conditions if air circulation is poor. These diseases weaken the plant and hasten decline.
   • Method: Ensure proper spacing between plants. Provide sturdy support (trellis, netting) for climbing.
8. Fertilize Appropriately:
   • Why: Sweet peas are heavy feeders. Provide adequate nutrients to support continuous blooming.
   • Method: Incorporate compost into the soil at planting. Fertilize lightly with a balanced liquid feed (e.g., flower fertilizer) every 2-4 weeks once blooming begins, diluted to half strength.
   • Avoid Excessive Nitrogen: Too much nitrogen promotes leafy growth at the expense of flowers.

By implementing these strategies, you can significantly extend the sweet pea season, allowing you to enjoy their exquisite beauty and fragrance for as long as possible, even as fall bloomers like chrysanthemums begin their show.

What Are the Best Practices for Caring for Chrysanthemums?

While sweet peas are fading, chrysanthemums are just beginning their show. Providing proper care for chrysanthemums ensures they deliver a spectacular display of late-season blooms, perfectly timed as the garden transitions to fall colors. They are relatively easy to care for once their basic needs are met.

Here are the best practices for caring for chrysanthemums:

1. Sunlight:
   • Full Sun: Mums need at least 6 hours of direct sunlight per day for abundant, vibrant blooms and strong, sturdy stems. More sun is usually better.
   • Why: Sunlight is crucial for flower bud formation and overall plant vigor.
2. Soil:
   • Well-Draining: Mums are very sensitive to soggy soil and root rot. They need excellent drainage.
   • Rich in Organic Matter: Prefer fertile, loamy soil with plenty of organic matter (compost). This provides nutrients and improves structure.
   • pH: Slightly acidic to neutral soil pH, ideally between 6.0 and 7.0.
   • Container Plants: If grown in pots, use a high-quality, well-draining potting mix.
3. Watering:
   • Consistent Moisture: Mums need consistent and adequate moisture, especially during hot spells and when developing buds and blooming. They are not drought-tolerant.
   • Avoid Overhead Watering: Water at the base of the plant to keep foliage dry, reducing the risk of fungal diseases like powdery mildew.
   • Monitoring: Use a soil moisture meter to check soil moisture before watering.
4. Pinching (Crucial for Bushy Growth and More Blooms):
   • Why: This is the most important pruning technique for garden mums. It encourages branching, leading to more flower buds and a denser, more compact plant. Without pinching, plants become leggy with fewer blooms.
   • Method: Starting in spring, when new growth is 4-6 inches tall, pinch off the top 1 inch of each stem.
   • Frequency: Repeat every 2-3 weeks until early July (in most regions). Stop pinching in early to mid-July to allow flower buds to form for fall bloom.
   • Consider: A sharp pair of gardening snips makes this easy.
5. Fertilization:
   • Moderate Feeders: Mums benefit from regular feeding during their active growth and bud development.
   • Method: Start fertilizing in spring after new growth appears. Use a balanced, water-soluble fertilizer (e.g., 20-20-20 NPK) or a specific flower fertilizer every 2-4 weeks. Stop fertilizing when buds begin to show color.
   • Caution: Avoid excessive nitrogen once buds form, as it can reduce bloom quality.
6. Deadheading (for Prolonged Bloom):
   • Why: While individual mum flowers are long-lasting, deadheading spent blooms encourages the plant to put energy into developing new buds and keeps the plant looking tidy.
   • Method: Snip off faded flower heads.
7. Provide Support (for Taller Varieties):
   • Why: Taller mum varieties, especially with heavy blooms, can flop or break in wind or rain.
   • Method: Use stakes, hoops, or cages to support them early in the season.
8. Pest and Disease Monitoring:
   • Common Issues: Watch for aphids, spider mites, leaf miners, powdery mildew (especially in humid/damp conditions).
   • Method: Inspect regularly. Address promptly with organic solutions like neem oil spray or insecticidal soap.
9. Winter Care (for Perennial Mums):
   • After the first hard frost kills back the foliage, cut stems back to 4-6 inches from the ground. Apply a layer of mulch over the crown for insulation in colder zones.

By diligently applying these best practices for caring for chrysanthemums, you ensure they produce a magnificent, long-lasting display of fall blooms, perfectly filling the void left by fading summer flowers like sweet peas.